The present invention relates to breech mechanisms for firearms and, in particular, it concerns a breech mechanism with a non-rotating breechblock.
In theory, a plurality of ammunition projectiles, herein referred to as xe2x80x9cbulletsxe2x80x9d, all having identical ballistic characteristics, fired from the same stationary firearm would all hit the same target at the same point of impact. Manufacturing techniques today produce bullets with substantially identical ballistic characteristics. The ballistic characteristics of a bullet are affected by variances due to manufacturing tolerances and any alterations to the bullet after manufacture. The most common of these alterations are nicks and scratches to the surface of the bullet caused by the loading process of the particular firearm in which the bullet is used. In general, the xe2x80x9ccartridgexe2x80x9d, herein used to refer to the combined bullet and bullet casing, is held in the chamber by a breechblock that rotates into a locked position. This rotating motion of the breechblock causes rotation of the cartridge which may cause the aforementioned nicks and scratches as the bullet is moved into the chamber and rubs against the lands and grooves of the rifling. These alterations, alone or in combination with alterations to the firearm due to ware, affect the accuracy by causing the bullets to hit the target in what is called in the art xe2x80x9ca groupingxe2x80x9d. The spread of a grouping is characteristic to each firearm, and varies with the distance to the target.
To avoid this problem, some shooters use single shot, manual loading firearms with non-rotating breechblocks. This is effective in reducing the nicks and scratches and the grouping characteristic of these firearms approach the point of being affected solely by the stability and characteristics of the firearm itself.
There are, however, situations where a single shot, firearm is inappropriate or undesirable, and a highly accurate repeating firearm is necessary. At present, what is referred to in the art as a xe2x80x9cbolt actionxe2x80x9d is the preferred repeating breech mechanism for those shooters who wish to attain high levels of accuracy in a repeating firearm.
The bolt action breech mechanism for a firearm especially a repeater weapon disclosed in U.S. Pat. No. 5,259,137 to Blenk et al. includes a non-rotating breechblock. The mechanism is, however, complex in both manufacture and maintenance. Further, the breechblock is locked in place by forcing normally closed locking fingers into an open position that locks the breechblock in a firing position.
Another problem of breech mechanisms of prior art is that of xe2x80x9chead spacexe2x80x9d. That is the distance from the surface of the breechblock that engages the rear of the bullet casing or cartridge forward to point at which the curvature of the bullet disengages the inside surface of the barrel. Optimally, the forward point of disengagement is contiguous to the rearward end of the lands of the barrel rifling. Deployment of the bullet in the chamber is determined by the position of the breechblock. The breechblock locking mechanisms of prior art utilize moving locking elements that are forced against, either rotationally or laterally, stationary members so as to push or draw the breechblock into a locked position. This may cause friction and thereby abrade the abutting surfaces. This may result in inaccurate deployment of the breechblock and therefore affect the head space such that the bullet is not deployed at the position in the chamber, either too far in or too far out.
There is therefore a need for a breech mechanism that provides a non-rotating breechblock that is locked in position with minimal abrasion of locking element such that head space in minimally affected, which is suitable for use with repeating firearms, and that is simple and easy to manufacture and maintain.
The present invention is The present invention is a breech mechanism that provides a non-rotating breechblock that is suitable for use with repeating firearms.
According to the teachings of the present invention there is provided, a breech mechanism for use in a firearm, the breech mechanism comprising: (a) a breech housing; (b) a slidingly displaceable breechblock at least partially deployed within the breech housing, the breechblock being displaceable between a firing position, and an ejecting and loading position, the breechblock terminating at a first end configured to interact with a bullet cartridge; and (c) a spring locking-element at least partially deployed within the breech housing, the spring locking-element configured so as to be biased to a normally locking state, the spring locking-element further configured such that as the breechblock is displaced from the ejecting and loading position toward the firing position is deformed out of the normally locking state, and as the breechblock reaches the firing position the spring locking-element springs back toward the normally closed state thereby locking the breechblock in the firing position.
According to a further teaching of the present invention, there is also provided, a releasing element at least partially deployed within the breech housing, the releasing element configured so as to deform the spring locking-element from the normally closed state thereby releasing the breechblock from the firing position.
According to a further teaching of the present invention, the breech housing is configured so as to hold the spring locking-element in a longitudinally static deployment.
According to a further teaching of the present invention, the spring locking-element is configured such that the normally locking state is an inwardly convergent closed state.
According to a further teaching of the present invention, the releasing element is configured so as to be slidingly displaceable and is deployed so as to circumscribe at least a portion of the breechblock, the releasing element being displaceable between non-releasing and releasing positions such that when the releasing element is displaced to the releasing position, the releasing element engages the spring locking-element thereby causing the radial expansion of the spring locking-element.
According to a further teaching of the present invention, the spring locking-element is configured substantially as a sleeve deployed within the breech housing, the locking element being configured such that the deformation from the normally closed state is implemented as substantially radial expansion of the locking element.
According to a further teaching of the present invention, the substantially radial expansion is at an end of the locking element that comes into contact with the breechblock such that as the breechblock is displaced from the ejecting and loading position toward the firing position, the breechblock causes the substantially radial expansion of the spring locking-element thereby allowing the breechblock to enter the spring locking-element such that the spring locking-element substantially circumscribes the breechblock, and as the breechblock reaches the firing position the spring locking-element springs back into the normally closed state thereby engaging the breechblock so as to lock the breechblock in the firing position.
According to a further teaching of the present invention, the spring locking-element is configured with a plurality of longitudinal slots along a portion of a length of the spring locking-element, the slots thereby defining between them, locking fingers that are connected to the spring locking-element at a first end, and free to spread substantially radially at a second end of the spring locking-element.
According to a further teaching of the present invention, there is also provided, engagement faces of the locking fingers configured at the second end of the spring locking-element, the engagement faces being configured such that as the breechblock is displaced from the ejecting and loading position toward the firing position, the breechblock engages the engagement faces thereby causing the locking fingers to spread radially so as to allow the breechblock to enter the spring locking-element such that the spring locking-element substantially circumscribes at least a portion of the breechblock.
According to a further teaching of the present invention, the engagement faces form an interior surface of the spring locking-element, the engagement faces being configured so as to be inwardly convergent.
According to a further teaching of the present invention, there is also provided, a locking ridge deployed on the locking fingers, the locking ridge configured so as to engage the breechblock.
According to a further teaching of the present invention, the breechblock is configured with the first end having a substantially radially enlarged portion, the enlarged portion terminating at the first end of the breechblock, the enlarged portion terminating at a second end in a locking shoulder, the locking shoulder configured to interlock with the locking ridge.
According to a further teaching of the present invention, the locking shoulder substantially circumscribes the breechblock.
According to a further teaching of the present invention, the releasing element is deployed so as to circumscribe at least a portion of a non-enlarged portion of the breechblock, the releasing element having an outside diameter at least equal to the outside diameter of the enlarged portion of the breechblock, the releasing element being displaceable in a direction substantially parallel to a length of the breechblock, the releasing element being displaceable between locking and releasing positions such that when the releasing element is displaced to the releasing position, the releasing element engages the engagement faces of the locking fingers thereby spreading the locking fingers radially so as to allow the displacement of the breechblock.
According to a further teaching of the present invention, the breechblock is configured so as to be non-rotating.
According to a further teaching of the present invention, the breechblock, the spring locking-element, and the releasing element are substantially cylindrical.
According to a further teaching of the present invention,sa longitudinal position of the spring locking-element within the breech housing is variable.
According to a further teaching of the present invention, the position of the spring locking-element is varied by at least one spacer deployed adjacent to at least one end of the spring locking-element.
According to a further teaching of the present invention, the displacement of the releasing element is actuated by rotation of a breechblock handle located adjacent to a second end of the breechblock.
According to a further teaching of the present invention, an axis of the rotation of the breechblock handle is substantially perpendicular to a line of displacement of the breechblock.
According to a further teaching of the present invention, a vector of displacement of the breechblock from the firing position to the ejection and loading position is parallel to a plane of rotation of the breechblock handle is parallel, such that the force applied to the handle rotates the handle thereby releasing the breechblock and the force then actuates the displacement of the breechblock.
According to a further teaching of the present invention, the spring locking-element is configured so as to define head space of the firearm.